PLANT OPERATION MONITORING DEVICE, CONTROL METHOD THEREOF, AND CONTROL PROGRAM THEREOF

PROBLEM TO BE SOLVED: To always execute a new request from an operator without interruption, even when the number of display windows has reached its limit, and to display again an erased window automatically or by a simple operation.SOLUTION: When a window limit management means 40 determines that the number of windows being displayed is equal to a set limit value, a window automatic erasure means 60 selects and determines windows to be automatically erased, out of the displayed windows, and erases the selected windows from the display of a display device 20 via a window display control means 50. An erased window storage means 70a stores the windows automatically erased. When it is decided that the number of displayed windows is less than the limit value, an erased window restoration means 80 selects and determines one of the erased windows and displays the selected window again via the window display control means 50.